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A woman and her 4-year-old daughter were killed after hitting a semi-truck at full speed. The accident happened Tuesday morning on northbound Interstate 5 near Camp Pendleton. The crash backed up traffic for at least 25 miles. NBC 7’s Wendy Fry has the latest. (Published Tuesday, Dec 10, 2013)

Updated at 5:05 PM PDT on Tuesday, Dec 10, 2013

A mother and her 4-year-old daughter were killed in a crash with a big rig Tuesday morning on northbound Interstate 5 in San Diego’s North County, officials confirmed.

The fatal collision involved the woman’s GMC Yukon and a Ralph’s grocery store big rig. Officials said the SUV plowed into the back of the semi-truck, possibly at freeway speeds, at around 9:20 a.m. near the I-5 checkpoint and scales.

2 Killed in I-5 Crash

A woman and child were killed in a crash with a big rig on Interstate 5 Tuesday morning. The fatal collision caused lane closures on the freeway and very heavy traffic for hours following the crash. NBC 7's Whitney Southwick reports. (Published Tuesday, Dec 10, 2013)

The big rig was stopped in a line of other big rigs attempting to access the San Onofre Commercial Vehicle Enforcement Facility.

Traffic investigators said it appears the driver of the Yukon did not apply the brakes prior to the deadly crash. Aerial images of the scene showed that the impact caused the SUV to become partially wedged under a portion of the big rig.

Woman, Girl Killed in I-5 Crash

Officials said the Yukon was wrecked so badly, investigators initially thought there might be a third victim inside. However, investigators later determined that was not the case.

The crash heavily impacted traffic on the I-5 for several hours. The CHP issued a SigAlert around 9:45 a.m., blocking three lanes on the freeway as investigators processed the site of the crash.

As a result, traffic on the I-5 was backed up for about 25 miles, with bumper-to-bumper traffic beginning just north of Oceanside through State Route 76. The CHP said they expected a long-term closure in the area as investigators collected evidence.

Motorist Cliff Whitekhaoss was stuck in the heavy traffic and said he was saddened by the incident.

“It’s an unfortunate day. I feel bad for the people who were in the accident – that’s pretty tragic,” said Whitekhaoss.

By 10:35 a.m., one lane had reopened, but the flow of traffic remained very slow. There was no timeline as to when the rest of the lanes would open again. Get traffic updates here.

By about 2:15 p.m., all lanes of northbound I-5 traffic had reopened, according to CHP officials.

The cause of the crash remains under investigation, but officials do not suspect alcohol as a factor.

No further details have been released about the victims just yet, other than their ages. The mother was 28 years old, CHP officials confirmed. The San Diego County Medical Examiner’s office will work to positively identify the woman and her daughter.

Officials said the driver of the big rig was not injured in the deadly collision.